A color filter is an essential component to a solid-state imaging device or a liquid crystal display. In particular, improvement in color separation property and improvement in color reproducibility are required for a color filter for a solid-state imaging device.
The color filter is formed with a colored area (a colored cured film) of a plurality of colors, and usually formed with at least a colored area (hereinafter, also referred to as a “colored pattern” or a “colored pixel”) of red, green, and blue. As a method for forming a colored pattern, first, in a first color, a coloring radiation-sensitive composition having a colorant of any one of red, green, and blue is applied, exposed, developed, and subjected to heat treatment, if necessary, to form a colored pattern of the color, and then a similar process of application, exposure, development, and heat treatment, if necessary, is repeated in a second color and a third color.
As the colorant in the color filter, a pigment has been widely used because the pigment has clear color tone and high tinctorial strength, and in particular, it is preferred to use a pigment which is micronized and simultaneously exhibits suitable color separation property.
Further, recently, for the solid-state imaging device, it is required to micronize colored pixels (for example, a colored pattern having a side length of 1.0 μm or less) for the purpose of improving resolution, but it is known that as the colored pixels are micronized, noise is increased.
A solid-state imaging device is utilized as an optical sensor in various applications.
For example, since near-infrared ray has a longer wavelength than visible light and thus is difficult to be scattered, near-infrared ray may be utilized for distance measurement, three-dimensional measurement, and the like. In addition, since near-infrared ray is invisible to humans, animals and the like, near-infrared light may be used to take photos of nocturnal wild animals, as well as to photograph persons without irritating the persons for security purposes, without being noticed by a subject even though the subject is illuminated with a near-infrared ray light source at night. Optical sensors detecting such near-infrared ray may be developed for various applications, and thus there is a need for developing a color filter that may be used for a solid-state imaging device that detects near-infrared ray.
For example, absorption of light is small in the near-infrared to infrared wavelength region, and a resin black matrix which is considered to have a high light transmittance in this wavelength region is known (for example, Patent Document 1), but since transmission of the near-infrared region is still insufficient, particularly, it is difficult to use the resin black matrix as an infrared transmission filter in the infrared sensor for detecting the near-infrared region.
Furthermore, in recent years, very thin (for example, a thickness of 1 μm) infrared transmission filters have been required, but as the thickness becomes smaller, the light-shielding property to visible light of the infrared transmission filter is likely to deteriorate (that is, noise derived from a visible light component easily occurs), and as a result, there is a problem in that the performance as the infrared sensor deteriorates.